Production of insolubilized filamentary products by the wet spinning of protein solutions



atented Jan, 124, 195C ITED STATES PATENT DFFICE PRODUCTION or msowemznn FILAMEN- i may raonnc'rs BY THE was SPINNING OF PROTEIN SOLUTIONS N Drawing. Application July 19, 1945, Serial No.

606,022. In Great Britain August 9, 1944 7 Claims.

The present invention relates to the manufacture of artificial filaments, threads, films or the like filamentary products obtained by the wet spinning of aqueous alkaline solutions of proient to apply to a continuously moving filamentary product. Accordingly it is desirable that for at least a considerable part of the period taken up by the insolubilisation treatment the filamentary teins, and especially of aqueous alkaline vege- 5 product should be in an untensioned condition table globulin and casein solutions, into saline and that most of the insolubilisation treatment aqueous coagulating baths of acid reaction and should take place after the tension employed in followed by a subsequent after-treatment of the the coagulation step or in any subsequent stretchfilamentary products that includes a treatment ing step, has been relaxed. While various treatwlth an insolubilising bath adapted to render the ments for the coagulated filamentary product coagulated protein usefully resistant to treatment intended to permit its insolubilisation to be efwith boiling water, hot acid dyebaths and alkafected in the untensioned condition have been line laundering solutions. proposed, they have been more or less unsatisfac- The filamentary products obtained by coagutory since the treatments have either taken an lation in the baths used for coagulating the exexcessively long time so that they cannot contruded protein solutions require to be subjected veniently be applied to the advancing filamentary to further chemical treatment to render them product, and usually they have not enabled deinsoluble in water and resistant to the swelling sirable extension of the filamentary product to or dissolving action of boiling water and weakly be maintained when the tension is relaxed. The acidic and alkaline solutions, such as are used most rapid and satisfactory treatment has been in dyeing and laundering. Such further chemito maintain the coagulated filament under tencal lnsolubilisation treatment is usually carried sion in substantially saturated sodium chloride out with the aid of formaldehyde, chromium salts solution, for instance, as described in British or aluminium salts, which are often referred to Specification 543,586, which was accepted on as hardening agents, in aqueous solutions con- March 4, 1942 and is an equivalent of U. S. Patent taining such compounds in association with other No. 2,358,427. When such treatment is carried solutes that increase their insolubilising action. out for about 10 minutes the tendency to longitu- Especially effective insolubilisation of the filadinal contraction of the filamentary material is mentary product may, for instance, be achieved thereby greatly reduced, and the subsequent inby the method described'in British Specification solubilisation step can be carried out on the re- 513,91G, which was accepted on October 25, 1939 laxed filamentary material, for instance, in hank and is an equivalent of U. S. Patent No. 2,347,677. or staple form.

It is known that the stretching of the coagu- We have now found that desirably high perlated filament prior to its insolubilisation is benemanent extension of the coagulated filamentary ficial to the strength of the resulting filamentary product, with corresponding advantage to the product. physical properties of the subsequently insolu- It has been proposed to stretch the still acid bilised product, can be attained if the coagulated. coagulated filaments in a saline bath sufficiently and if desired already somewhat stretched, filahot to make them plastic, but when a bundle of mentary product is stretched in an aqueous bath parallel filaments is stretched in this manner 40 capable of swelling the filament and containinga they tend to stick together irreversibly when they solute adapted to bufier the fibre to a pH approxare first wound up. When the saline bathis at a imately the iso-electric point of the protein from lower temperature this defect is not evidenced, which it is, derived, and then washing the but the amount of stretch that can be applied stretched filament without relaxing the tension without breaking the filaments is less, and the in an aqueous non-solvent bath adapted to shrink stretched filaments are highly contractile. it.

The chemical insolubilisation treatment neces- According to the present invention, therefore, si-tates, for its progress to such a stage that the the method for the manufacture from alkaline products become capable of drying without stickvegetable globulins and casein solutions of artiing together, a much longer time than is convenficial filaments, threads, films or the like fila- 3 inentary products of the kind hereinbefore defined comprises stretching the coagulum, obtained by the wet spinning of said alkaline solutions into saline coagulating bath of acid reaction, in an aqueous medium capable of swelling the coagulum and at a temperature such that the swollen and stretched coagulum remains contractile, said aqueous medium containing a solute such that the aqueous medium around the coagulum will approximate the isoelectric pH of the protein of the coagulum whereby the said aqueous medium around said coagulum will be of the acidity least capable of dissolving said protein, washing the swollen and stretched coagulum without relaxing the tension in an aqueous nonsolvent non-hardening bath adapted. to shrink it, whereby it is rendered non-contractile, and treating the resulting wet coagulum without the application of tension in an aqueous saline insolubilising bath adapted to render the coagulum usefully resistant to treatment with boiling water, hot acid dye baths and alkaline laundering solutions.

The acidity of the coagulated filamentary material emerging from the acid saline coagulating bath is preferably reduced by drawing it through one or more aqueous non-solvent baths, for instance, neutral saline baths, before subjecting it to the action of the swelling bath containing the buffering solute.

The buffering solute may comprise a weak base or feebly alkaline salt of a strong base with a weak acid, and may also comprise feebly acidic salts or weak acids in addition if necessary. As examples of weak bases and feebly basic salts, may be mentioned aniline, ortho-toluidine, sodium acetate, sodium citrate, and di-sodium hydrogen phosphate. If necessary citric acid, acetic acid, phosphoric acid, boric acid or mono sodium dihydrogen phosphate may be included. It will be understood that the total electrolyte concentration of the bath must not be excessive in order that it should retain the capacity to swell the filament. The bath may be used at atmospheric or preferably at a somewhat raised temperature.

The subsequent shrinking bath may be, for instance, a concentrated solution of a neutral salt or an organic dehydrating agent such as alcohol in water or some other non-solvent solution of like osmotic pressure. i. If desired a preliminary stretch may be given to the filamentary product before it is introduced into the swelling bath of buffering properties in which it is stretched, for instance, in the coagulating bath or some intermediate bath such as a neutral saline bath.

The process according to the present invention has the advantage that the shrinking treatment applied to the stretched filament still under tension does not necessitate nearly such a long time as the treatments hitherto proposed for application to stretch the filament in order to render it possible to complete their insolubilisation without tension. Hence it can be more conveniently carried out on an advancing filament. Moreover, it enables a higher stretch to be applied, without rendering the filaments sticky, than the hitherto known stretching processes.

Example 1 A solution containing by weight of pea nut rotein 1.3% caustic soda and with a viscosity of 200 poises is extruded at the rate of 40 c. e. per minute through a spinneret containing 500 holes each .09 mm. in diameter into a coagulating bath of 20% sodium sulphate and 2% sulphuric acid in water at 28 C. The filaments thus formed are drawn oil over a 16 cm. diameter godet wheel rotating at revolutions per minute and passed through a second bath of 20% sodium sulphate in water at 40 C. and are collected on a swift at a peripheral speed of 60 metres per minute. The filaments are thereby extended about one third of their length. After being kept on the swift in the sodium sulphate bath for about 20 minutes they are removed from it and placed in saturated brine at 20 C. A length of the filament is then withdrawn from the brine and stretched to twice its length in 0.4% solution of aniline in water at 50 C. over a period of one minute and the extended filament is then transferred to a saturated sodium chloride bath and held for one minute in the stretched condition in the bath, which is at 40 C., by which time the tension may be relaxed. The pH of the filament in the aniline bath is about 4.5.

The filaments are then transferred to an insolubilisation bath containing 1 formaldehyde and 2% hydrochloric acid in saturated sodium chloride brine at 38 C., and are allowed to remain in this bath for eighteen hours, by which time they are capable of withstanding treatment in a bath containing 0.1% sulphuric acid and 0.25% sodium sulphate for 90 minutes at 97 C. length of the filaments is 65% greater than that of the filaments taken from the swift, and the diameter of the filaments is correspondingly reduced. The iso-electric pH of pea nut protein is about 4.5.

Example 2 In this case the coagulating bath is the same as in Example 1 and the freshly coagulated filaments as they are advanced are given a preliminary stretch in a bath of 20% sodium sulphate in water at 40 C. as in Example 1, but instead of being collected on a swift they are introduced from the tensioning roller into a bath consisting of 0.4% aniline solution in water at 50 C., in which they are further stretched to twice their length, and from this stretching bath the filaments pass over a series of successive pairs of skew cylindrical rollers driven to rotate at the same peripheral speed in parallel planes, over which they are wound in a helix so that they take one minute to complete the traverse. These skew rollers are immersed in saturated sodium chloride solution at 40 C., and thus hold the continuously advancing stretched filament at its stretched length in the saturated sodium chloride bath for one minute.

The advancing filaments are collected and cut into staple fibre. The staple fibre is then transferred to the insolubilisation bath described in Example 1, in which it is allowed to remain for eighteen hours at 30 C.

We claim:

1. In a method for the manufacture of artificial filamentary products of protein material by the wet-spinning of alkaline protein solutions into acidic saline coagulating baths, the steps which comprise stretching the coagulum in a weakly alkaline, non-hardening, swelling bath comprising an aqueous solution of an aryl amine at a temperature of between 20 C. and 50 C., washing the swollen and stretched coagulum without relaxing the tension with an aqueous, nonsolvent, non-hardening, coagulum shrinking bath and then insolubilizing the resulting product in untensioned condition in an acidified concentrated saline formaldehyde bath.

2. The method as claimed in claim 1, wherein said coagulum shrinking bath is a concentrated solution of a neutral salt.

3. The method as claimed in claim 1, wherein the coagulum is subjected to a preliminary stretching operation in an aqueous, non-swelling bath prior to said stretching step in said weakly alkaline swelling bath.

4. The method as claimed in claim 1, wherein said coagulum shrinking bath is an aqueous solution of a water soluble alcohol.

5. In a method for the manufacture of artificial filamentary products of peanut protein material by the wet-spinning of alkaline peanut protein solutions into acidic saline coagulating baths, the steps which comprise stretching the coagulum in a weakly alkaline, non-hardening, swelling bath comprising an aqueous solution of an aryl amine at a temperature between 20 and 50 C., washing the swollen and stretched coagulum without relaxing the tension with a concentrated aqueous solution of a neutral salt and then insolubilizing REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,211,961 Meigo Aug. 20, 1940 2,266,672 Wormell Dec. 16, 1941 2,290,789 Wormell July 21, 1942 2,338,916 Ferretti Jan. 11, 1944 2,358,427 Traill Aug. 19, 1944 2,409,475 Cline Oct. 15, 1946 

1. IN A METHOD FOR THE MANUFACTURE OF ARTIFICIAL FILAMENTARY PRODUCTS OF PROTEIN MATERIAL BY THE WET-SPINNING OF ALKALINE PROTEIN SOLUTIONS INTO ACIDIC SALINE COAGULATING BATHS, THE STEPS WHICH COMPRISE STRETCHING THE COAGULUM IN A WEAKLY ALKALINE, NON-HARDENING, SWELLING BATH COMPRISING AN AQUEOUS SOLUTION OF AN ARYL AMINE AT A TEMPERATURE OF BETWEEN 20*C. AND 50*C., WASHING THE SWOLLEN AND STRETCHED COAGULUM WITHOUT RELAXING THE TENSION WITH AN AQUEOUS, NON-SOLVENT, NON-HARDENING, COAGULUM SHRINKING BATH AND THEN INSOLUBILIZING THE RESULTING PRODUCT IN UNTENSIONED CONDITION IN AN ACIDIFIED CONCENTRATED SALINE FORMALDEHYDE BATH. 